When the capacitors leak, they leak a sticky goo. Most of the washing recommendation is to remove that corrosive and (apparently) conductive goo.

So a pure distilled water wash probably wouldn't help, unless it was hot enough to dissolve the goo.

Detergents, solvents and hot dishwasher washing all serve the same purpose. Absent a careful study, it really boils down to which method you prefer. I like to use 91% alcohol and a soft bristle toothbrush, followed by distilled water, just because all the ingredients are easy to get, come is small(ish) bottles and aren't likely to make a big mess.